A need arises in many applications for permitting the transmission of an electrical signal between areas of different pressure. In tanks which contain gas or fluid under pressure, for example, it is often necessary to conduct the signal into the tank to control a solenoid-operated valve. Because the tank must be breached in order to pass a wire through to the valve, some provision must be made for maintaining a seal against the leakage of contents out of, or contaminants into, the tank.
One method of accomplishing this seal in through the use of epoxies or other potting compounds. U.S. Pat. No. 2,987,570, for instance, discloses a fluid-tight connector structure which includes a vulcanized sleeve molded into place. U.S. Pat. No. 3,352,963 shows a different design in which a low pressure side conductor rod and a high pressure side conductor rod are joined by a connector provided with an external conical sealing surface received within an insulating sleeve. The sleeve and the connector are received within a pair of nested concentric metal sleeves each having complementary tapered sealing surfaces and seats. A hollow loading nut houses the sleeves and connector and draws them together into sealing relation when the nut is threadably secured to a wall.